Roller carriages for bridge structures have been provided heretofore and generally utilized a rocker carrier with a lateral stud pivotally engaged in the outrigger for the truss structure which is to be displaced on rails or other support members via such roller carriages. A pair of rockers are in turn mounted on the rocker carrier and each of the rockers may be provided with a pair of rollers.
Typical of such structures are those described in German patent document DE OS 25 30 359 and DE GM 93 08 340.8.
In the system of DE OS 25 30 359, the support pin of the rocker which is received in the rocker carrier and thus supports the rocker and its pair of rollers on the rocker carrier is force-fitted or frozen in place. The press fit of the pin which is thus separable from the rocker body creates problems in, for example, stress between the bolt and the rocker carrier. Since this pin must conduct the forces between the rocker carrier and the rollers, with time the bore in the rocker carrier tends to enlarge and the resulting play can create problems in the travel of the carriage. The carriage becomes unreliable with time.
In the system of DE GM 93 08 340.8, an attempt is made to avoid these drawbacks by casting the support pin in situ. While this approach has been successful in providing a tight fit with less chance of damage with time, in practice the approach is expensive and complex and tends to be avoided for economic reasons.